The Plato.Roles module is a core module for Plato and cannot be disabled via the features page. The Plato.Roles modules offers the user interface available via the administrator dashboard to add, edit & delete user roles within Plato.
In addition Plato.Roles also adds additional user interface elements allowing administrators to associate users with any number of roles.
You can see Plato.Roles in action below allowing us to associate one or more roles with a user we are editing...
For further information please see Roles.